Lecture 13: Life History Tradeoffs

Question 1

Not all individuals contribute in the same way to

Answer 1

population dynamics

Question 2

An organism’s life history is

Answer 2

a record of events relating to its growth, development, reproduction and survival

Question 3

Life history characteristics include:

Answer 3

Survival and mortality rates
Age and size at sexual maturity
Amount and timing of reproduction

Question 4

Life history strategy of a species

Answer 4

The overall pattern in an average timing and nature of life history events
Shaped by how the organism allocates energy and resources between growth, reproduction, and survival
Associated tradeoffs with allocation patterns

Question 5

Within a species, individual strategies may differ because of

Answer 5

genetic variation, environmental conditions, or both, which can affect the species success

Question 6

Natural selection favors individuals

Answer 6

whose life history traits result in their having a better chance of surviving and reproducing (fitness)

Question 7

All organisms face ___ and _____

Answer 7

constraints
ecological trade offs

Question 8

Complex life cycles

Answer 8

At least two stages with different body forms that live in different habitats and eat different foods

Question 9

Metamorphosis

Answer 9

Ex of complex life cycle
Abrupt transition between larval and juvenile stages

Question 10

Complex life cycles found in

Answer 10

Common in insects, marine invertebrates, amphibians and some fishes
Many plants, algae, and protists also have complex life cycles

Question 11

Trade offs along life history are ___

Answer 11

ubiquitous
investments: energy, resources, time

Question 12

Life history trade offs involve

Answer 12

allocate energy to current reproduction OR grow bigger first (risking death in the meantime) and then reproduce

few large offspring or many small offspring

Question 13

Allocating resources to reproduction from trade off can

Answer 13

decrease an individual’s growth rate, survival rate, or potential for future reproduction

Question 14

Ricklefs observed trade off between

Answer 14

annual fecundity and annual survivorship in bird species

Question 15

different morphologies and behaviors are

Answer 15

adaptive at different life cycle stages

Question 16

___________ over the course of the life cycle are responsible for distinctive patterns in the life histories of organisms

Answer 16

Differences in selection pressures

Question 17

Organisms have various mechanisms to protect

Answer 17

small life stages
Ex. Parental investment

Question 18

Dormancy

Answer 18

State of suspended growth and development in which an organism can survive unfavorable conditions
Ex. small seeds, spores, eggs, and embryos are best suited to dormancy as less metabolic energy needed to stay alive
some larger animals can enter dormancy

Question 19

_______ is common in complex life cycles

Answer 19

functional specialization of stages

Question 20

Ex. of functional specialized of stages

Answer 20

In many insects the larval stage is specialized for feeding and growth; the adult is specialized for dispersal and reproduction

Question 21

Luna Moths

Answer 21

Extreme example of functional specialization of stages:
Adults only have vestigial mouthparts and no digestive system
Eye spots to reduce predation
Wing tails create false target for bats to attack and moth breaks off tail (anti predator control)

Question 22

Are there general patterns/categorizing species in the tradeoffs that organisms make in life history strategies?

Answer 22

Grime’s CSR triangle
r vs. K selected species

Question 23

Grime’s triangle

Answer 23

Makes general categories of life history syndromes based on the environment
Stress vs. disturbance

Question 24

How is Grime’s Triangle Organized?

Answer 24

Increasing disturbance from top to bottom
Increasing stress from right to left
Increasing competition from bottom to top

Question 25

Stress-tolerant plants

Answer 25

Bottom left in Grime’s Triangle
Adapted to high stress, low disturbance habitats
Ex. Ivies, cacti

Question 25

Ruderal plants

Answer 25

Bottom right in Grime’s Triangle
Adapted to high disturbance, low stress habitats
Ex. dandelions, lawns in front of house

Question 26

Competitive plants

Answer 26

Top of Grime’s Triangle
adapted to low stress, low disturbance habitats
Ex. birch trees
Tend too be competitive

Question 27

What does Grime’s Triangle not include?

Answer 27

plants adapted to high stress, high disturbance

Question 28

To account for high stress high disturbance use different model CSR triangle of Grime

Answer 28

Stress= Habitat productivity
Disturbance= habitat duration
Original triangle with stress tolerators, competitors, and rooters is only half the space = tenable triangle (places plant can live)
High stress, High disturbance (Low habitat productivity, low habitat duration) represented in untenable triangle (plants do not live)

Question 29

Categorize species by life history characteristics through:

Answer 29

fast to slow life history

Question 30

Categorizes of syndrome for fast to slow life history

Answer 30

r-selected
K-selected

Question 31

Fast r-selected

Answer 31

Species that do not do well under high resource conditions, immediately after disturbance

Question 32

Slow K-selected

Answer 32

Species that are competitive and do well when resources are limited

Question 33

Timing of ________ can be of critical importance

Answer 33

seasonal life history activities

Question 34

Ex. importance of timing of seasonal life history

Answer 34

A bird that migrates north too early in spring may starve if no food is available
Long term data show that many species initiate spring activities earlier, apparently in response to climate change

Question 35

Shifts in timing of seasonal don’t …

Answer 35

always keep pace with climate change

Question 36

Ex. of how shifts in timing do not keep pace with climate change

Answer 36

Snowshoe have fur changes to white in winter, but the timing has not changed, even though snowfall begins later in the year

Question 37

As shifts in timing do not keep pace with climate change, what can be result

Answer 37

Camouflage mismatch and increased mortality from predators